1. Field of the Invention
The present invention relates generally to seatbelt restraint systems for vehicles and, more particularly, to a seatbelt pretensioner for a seatbelt restraint system in a vehicle.
2. Background
Seatbelt restraint systems for restraining an occupant in a vehicle seat play an important role in vehicle crash situations. Seat restraint systems commonly have a lap belt section and a shoulder belt section. In general, the lap belt section and the shoulder belt section are connected together at one end. A seat restraint system includes a buckle at the connected end. The seat restraint system also includes a latch plate connected at one end by seatbelt webbing that is attached to the vehicle structure and/or the seat. The buckle receives the latch plate to be buckled together. When the buckle and the latch plate are buckled together, the seat restraint system restrains movement of the occupant during a collision.
OEM vehicle manufacturers often incorporate pretensioning devices, which tension the seatbelt prior to full impact of a vehicle, to enhance restraining the occupant to the seat. One type of pretensioning device is a pyrotechnic lap pretensioner (PLP). Various designs are known, including a type of PLP which uses a cable to connect a piston at one end to seatbelt webbing at the other end. When a collision occurs, a pyrotechnic charge is fired, producing gas which pressurizes a gas chamber within a tube, to force the piston down the tube. Since the seatbelt webbing is ultimately connected to the piston via the cable, the seatbelt moves in conjunction with the piston, tightening the belt around the occupant.
Many conventional seatbelt retractors employ a pretentioner for forcedly winding seatbelt webbing on a spindle upon abrupt deceleration of a vehicle due to collision to prevent the seatbelt webbing from being loosened. A number of conventional seatbelt retractors are identified and described in U.S. Pat. No. 8,042,758, the content of this patent is incorporated herein by this reference.
Once deployed, most pretensioners retain pressurized gas within the interior of the tube. This pent up pressurized gas presents a risk of personal injury during disassembly.